Your photo of the Rose prescription reminds me of the old doctor's script. The R with the added x, was the method of prescribing medicines.
There are so many chemicals and treatment on the market for treating, or attempting to treat various plant ailments. Sad to say, in most cases once a plant shows signs of a diseas etc, it is a bit late. Thankfully the foliage is usually first to show the problem and in the case of Black Spot and other attacks, most treatments will not cure the problem. Damaged affected leaves are best removed and incinerated, do not compost. Application of available chemicals can help prevent or minimise further attacks.
Keep thin straggly growth cut away, also avoid branches that cross over. Where possible try and keep the stem growth balanced. Meaning not allowing too much bare stem developing between leaf formation. Roses are hungry plants so regular feeding is required and as they develop, they can get very thirsty. Try and learn what you can about identifying the plants health problems from the signs and symptoms displayed by the leaves.
They look very scraggly. Get a good rose fertilizer and feed them per the instructions. Also since the veins of the leaves are still green and the parts in between yellow and brown, it could be the common problem of magnesium deficiency. Feed them with some Epson Salts and water it in. Affects Tomatoes, potatoes, peppers and other plants too. Causes vary from magnesium leaching out of the soil to too much potassium in fertilizers. But it's an easy cheap harmless fix so worth trying anyway.